Palm oil is obtained by different
traditional and mechanized methods ranging from processing uncooked or cooked
fruits to centrifugation of mashed boiled or de-pericarped palm fruits. Palm
oil and palm kernel oil can be extracted form oil palm fruits mesocarp and palm
kernel respectively, using very simple equipments and techniques. However,
specialized equipment and considerable still and knowledge are required to
obtain a high yield of oils of good quality. (Anon, 1972)) Hence, the
technology of palm oil production has advanced in recent years and new
technological innovations are being introduced yearly to minimize losses,
achieve optimum process efficiency and quality (Jacquermard, 1998).
Different methods are employed
during the processing of palm fruits into palm oil these include:
A. TRADITIONAL
METHOD:- this method was and its still in usage long before the inventory
of machineries. This method is slightly modified by the introduction of the
curb press. The method differs from one community to another, the method
currently used by most processors in many parts of Nigeria include the following
steps.
Flow chart of the processing
of palm oil by the traditional method. (Ndon, 2006)
OBTAINING LOOSED FRUITS: the harvested bunches are cut into sections, kept in
heaps 2-4 days, covered with banana/plantain leaves or sprinkled with water to
loosen. Most traditions will not allow the fruits to ferment but will start
processing immediately it is harvested.
CLEANING/ WASHING:- the loose fruits are washed with clear water to
remove any trace of dirt.
BOILING:
The washed fruits are boiled as pounded in large wooden mortar with wooden
pestle until a mixture of nuts and crushed pulp obtained
PRESSING:- The hot pounded mixture crushed pulp and nuts are
pressed using had and warm water to separate the fibre, pulp and nuts from the
oil/water mixture, a sieve in used to filter out the fibre and nuts.
CLARIFICATION:- The crude oil obtained after pressing contains water
and other impurities. The oil is brought to boil for about an hour depending on
the volume of the extract (Ndon, 2006). It is then left to cool with one oil
which flows to the top with water and other impurities remaining at the base of
the pot.
EVALUATION OF TRADITIONAL PALM OIL
EXTRACTION TECHNOLOGY
Traditional methods employed for
palm oil production are only 50 percent efficient. The potential for palm oil
production in Africa region is so enormous that it is important that the
techniques employed are carefully studied and improvements made whenever
possible (Krodylas, 1990).
Cleanliness of the processing
equipment directly affects the quality of the end product. If the equipment is
not thoroughly cleaned afterwards, the residual film of oil on surface is
readily contaminated y airborne microorganism fungi and moulds. These then
becomes a primary sources of microbial infection the enzymatic breakdown of
palm oil occurs very rapidly and the extent of which the oil stays in touch
with contaminated equipment. (Kordylas, 1990).
B. POWER
MECHANICAL MILL
Sterilization of
bunches
|
Stripping of fruits
from bunches
|
Digestion
|
Digestion
|
Clarification
Flow chart of oil producing
methods in industrial way (Ndon, 2006)
QUALITY
CONTROL OF PROCESSED PALM OIL
If fruits are kept for server days
after harvesting, it will be invaded by moulds which will starts to grow on the
base of detached fruits or on inflicted wounds and will gradually spread and
cause the fruits to begin to rot. When this happens, the FFA of the oil begins
to rise and tat the same time the oil undergoes oxidation leading to reduced
bleach ability. Thus if fruits has to be stored for several days before it
could be milled, it would be preferable to store it fresh unless, there were
facilities for resterilizing it everyday thereby killing the molds.
After harvesting, the palm fruits
bunch are tested on arrival at the mill. Tests are conducted on the quality of
palm oil, the proportion of broken kernels, impurities, moisture and FFA
content of the palm kernel oil. While the sludge (Palm kernel cake) which is
used as animal feed is tested for the presence of afflatoxins (Jacquamard,
1998).